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PATENTED MAR 'f3 |868 JOHN MIX, OF WEST CHESHIRE, CONNECTICUT.

Letters Patent No. 75,182, dated rlfarch 3, 1868.

IMPROVEMENT IN MANUFACTURING GIMLETS.

dlp .sagome referat tu in tigen trtters @anni mit uniting gaat nt tigestmt.

TG ALL WHOM IT MAY CONCERN:

Be it known that I, JOHN MIX, of West Cheshire, in the county of .NewHaven, and State of Connecticut, have invented a new and usefulImprovement in the Manufacture oi' Gimlets and GimletBits, of which thefollowing `is a full, clear, and exact description, reference being hadto the accompanying drawing, forming part of this specification, and inwhich- Figures 1 and 2 represent face views of lower dies used in myimproved mode of manufacturing gimlets or 'gimlet-bits, and

Figures 3 and 4 transverse sections of the same, with work or stockarranged" therein; iig. 4 also showing the application of an upper diein connection with the lower one, with the work arranged in betweenthem; iig. 3 being taken as indicated by the line x in fig.' 1, and iig.4 taken as denoted by the line e e in iig. 2.'

Figures 5, 6, T, 8, and 9 illustrate longitudinal views of gimlets orgimlet-bits in various stages of their manufacture, and under differentforms of construction.

Similar letters of reference indicate corresponding parts. Y

In the ordinary process of making gimlets or gimletbits having more orless twist, it is usual 'to swage the cutting-portion ofthe gimlet orbit, including the twist, from a blank having a'lattened form on its oneside or face, and rounded form on its opposite side, in a straight lineor direction with the shank of the gimlet or bit. Under such process ormode, however, of making such articles, the after-operation of wringingthe blank to form the twist necessarily involves, from the shape giventhe blank or stock, a regular tapering character to the latter, from theroet of the attened portion to the point, which is objectionable, ascausing the greatest swell too far from the point, and into, forinstance, the pod of the gimlet or bit, which after-part should -formedof a taper or diminishing diameter in a backward direction, for thepurpose of establishing clearance of the cuttings in contradistinctionto cutting. This desideratum my invention accomplishes by giving-t0 the.I forward part of the llattened portion of the blank orstock of which itis desired totorm the twist, a onesided or bent lateral direction totheaxis of the stock, and afterwards rolling over said bent portion toiformthe cutting-twist, which gives the largest swell at the root of thelatter, and establishes a cleaner, and, it may be described as abrupt,finishing-cut at such point', leaving the balance of the ilattenedportion, whether grooved, twisted, or plain, of a regular diminishingtaper from the root of the cutting-twist. 1.

Referring to the accompanying drawing, I take a piece ofround-bar steel,of the required length for the gimlet or bit, and slightly bending andpointing it, insert it, lwhile heated, in a lower die, A, g. 1, and,bringing' down a; suitable upper die'or punch, give to the stock B aattened form on its one side or face for a portion of its length fromthe point, as, for instance, represented in fig. 5, where it is shown asilattened from the -poinft' a as far up as b, the same beingof a roundconliguration on its opposite side; and,.through the shape ofthe dies, Ifurther give a lateral direction or bend to the more forward part ofsuch flattened portion, as from a to c; Where it is desired to form theafter-part ofthe flattened portion, as from c to b, of a grooved orpod-like form, d, figs, 6, 8, and 4, then the upper die or punch, C, andlower die, A', are constructed t9 thus formsueh part, as shown in iig.4, but the after-part of the flattened portion may, if desired, be left`plain or level, as at e, in figs; 5 and 7. Whatever the configuration,lhowever, given to the after flattened portion ofthe stock, the frontbent forwardpart of the latter, as from a to c, ligs. 5 and 6, is rolledover, by, say, means of tongues', or otherwise, to forni acutting-twist,f, gs. 7, 8, and 9, from thc parte as a base, where theflattened portion is widest. i This brings the point a of the stock outof itslateral position into the axial line of the latter, and gives thelargest swell or biggest diameter at the root of the cutting-twist, witha gradually-diminishing taper backwards from that point for theremainder of the ilattened portion, which construction is in no wayanalogous to wringing the stock with the whole otl the flattened portionin the saine straight line as the remainder of it, and which ordinaryconstruction gives the biggest swell in the roar of the cutting-twistf,that, to establish an easy and clear cut, should have immediate relief,and the after-portion be free to enter theV cavity made by the cutting-ltwist, with roomy escape for the cuttings, but in no other way aiding orforming the cut, or binding on the hele made on the projection orinsertion of the cutting-twist through the latter.

Fig. 7 represents a giml'et or ginilet-bit constructed as from the blankshown in iig. 5, with the after flattened portion c, from c to b in fig.5, left plain or straight; fie. 9, a gimlet or. bit constructed from thesame blank, but with the after lnttened portion twisted inl the ordinaryway, by wringing the stock, as at g, after the cutting-twistf has beenformed by rolling over the bent portion of the blank; and fig. 8 shows ogimlet or bit formed from the blank represented in fig. 6, with npod-like configuration, d, given it in renr of the cutting-twist. Thusthe gmlet or gimlet-bit, made according to this, my improved mode orprocess of manufacture, may either be part twist and nt, 'part twist andpod-form, or Wholly twist.

The usual finishing and polishing of the gimlet or bit, and cutting ofa. screw-thread on its forward end or point, may be subsequently done inthe ordinary manner.

What is here claimed, and desired to be secured by Letters Patent, is

The method herein described of forming blanks for gimlets orgimlet-bits.

JOHN MIX.

Witnesses:

J'. W. CooMBs, A.- LE CLERC.

